Earlier quoted context omitted.
"I genuinely do not understand why other countries put up with this." Maybe because there is no drop in replacement of microsoft and microsoft dependant tools? So yes, one can (and should) build them. But the market right now is not offering this yet.
For many services there are drop-in Replacements available. I don't see what's so special about Mail or Calendar from Microsoft vs other vendors. The Quality is also Shit. I get some stupid Errors when trying to Access OWA every other day. Then I have to reset cookies/cache and can login again
Microsofts advantage is ActiveDirectory integration. Centrally managed users and machines, every user, every application, every service authentications through the AD.
Organizations opt for Teams all the time, because it's part of the package and fully integrated. There's no reason they couldn't pick something else, but why deal with it when Teams just work (sort of).